JSF: Check for PostBack.

I have a form with several selectOneMenu's that are populated from a Database. On this form I have one menu option that only changes whether or not a specific panel is hidden or visible. Because this has to submit back to the server, I realized that every time I change this option, all my selectOneMenu's are going to hit the database again to get their values. This is not good.

In .NET (don't smite me) there is a check that is basically something like if(!Page.IsPostBack) and what that does is checks to see if the page was submitted back to itself and if not, it will enter that loop.

I need something similar in JSF so that if the page is posted back, I don't need to get all those values from the database again. It should just use what values the backing bean already has.